Sand classifying and dewatering apparatus



April 13, 1954 w. E. SAXE 2,675,128

SAND CLASSIFYING AND DEWATERING APPARATUS Filed Dec. 23, 1948 TSheets-Sheet 1 igwam".

April 13, 1954 w. E. sAXE SAND CLASSIFYING AND DEWATERING APPARATUS Filed D60. 23, 194a 7 Sheets-Sheet 2 April 13, 1954 SAXE 2,675,128

SAND CLASSIFYING AND DEWATERING APPARATUS April 13, 1954 w, SAXE 2,675,128

SAND CLASSIFYING AND DEWATERING APPARATUS Filed D80. 25, 1948 7 Sheets-Sheet 4 5y Q9 ,52 MM.

April 13, 1954 w. E. SAXE SAND CLASSIFYING AND DEWATERING APPARATUS Filed D80. 23, 1948 7 Sheets-Sheet 5 a B2 0 me w w Mid u a 5 W; w Q 4 y a a a MW I: a T M M O E 9 w L .L w m w O 1: 2 w a, m Iln 4 7 yllllfillrllllllflv 0 0 7 6 Z April 13, 1954 w. E. SAXE 2,675,128

SAND CLASSIFYING AND DEWATERINCAPPARATUS Filed Dec. 25, 1948 7 Sheets-Sheet 6 1 1 1i |1|!ii 1.1-1 1 Q 1 X W vb /u April 13, 1 w. E. SAXE SAND CLASSIFYING AND DEWATERING APPARATUS Filed Dec. 25. 1948 7 Sheets-Sheet 7 Patented Apr. 13, 1954 Walter E. Saxe, Pasadena,'Calif., assignor to The Conveyor Company, Inc., Los Angeles, Calif., a corporation of California v Application noen por 23, 194s, Serial No. 7.003

This invention relates to mechanical structure 'for the removal of excess liquid "from various liquid-containing masses commonlykn'own as pulps which comprise the liquid and varying proportions'of solids. More especially; the invention relates to apparatus for separating the water content from granular materials such as wet sand and similar siliceous or mineral bearing pulpsproduct. it being a still further object to provide means for applying liquid to those portions of the apparatus from which the dried material has been dischargedwhereby to condition them forfurther reception of pulp to be treated.

Q A further object is to provide a de-wvaterine,

structure in which bristles in a substantially fiat brush formation may be employed to accomplish the desired rapid liquid flow without loss of One objector theinvention is to provide an m fines or lo ing, of nw i h b istles are emefficient apparatus capable of speedily reducing ployed in the bottoms or sides of buckets or other the water content of large volumes of "wet; solid containers as filtering or separati g agents materials to very low proportions, for" example, throug Which excess wa e a to as low as about 5% from water contents as other Ob c s a d adv ta es of this invenhigh as about 80%. Thus, it is desirable to 15 tion; together with-the various features thereof, reduce the water content" of sand loaded at i becomewpparent those S ed in this large and plants t h a minimum t t water art upon reference to the following specification will not drip vfrom trucks or railway cars durtheaccompanying w s wherein Ce ta ing transportation, and at the sarh'etime haulembodiments of the invention are illustrated for age and freight costs otherwise payable on such go t e pulposeof x mplifi ation. While reference excess water are d, Similarly, such pe is generally made in the descriptive matter to a ations as cyanidin ggold sands'by leachingfspeed water and sand pulp, it is to be understood that recovery of enriched leaching solutions'without ifl h fin fi ti s useful a in onnection With waiting for percolationthrough the sands is 'ecoother p op i liquid Carrying olids. nomically desirable as isgoodpre drying before 25 drawings! 7 L fire dryingof sands for glass manufacture and s '15 a elevatiollal View f O e end of t like a I i l j 1 apparatus embodying the improvements hereof, It is also an objector the inventiontoprovide this viewbeing-taken from the right side of Fig. 2 in the same apparatus means for reducing the a xi by the arrow; water content of sands vWhile providing also for 3,0 2 s Vertical tudinal section taken classification of the sands before "deewateifing approximately from the line of a and without thenecessity'of employing separate 1 i 1 a vertical s section t ken pproxclassifying apparatus ahead of the tiewatering ly on the line of 2; means. An incidental object is to provide such i 4 is an a e Sectifmal detail of one a classifying device means for relying upon' a thebucket conveyors and associated mechavariable rising liquid columnor a variablestreain .Seen in i 3; length, or a variable'area of the risin c u Fig. 5 is a sectional view taken approximately as a classification agent. I QPFP line 7 of i An additional object is to provide efi'icient'de- 6 ma considerably enlarged m t ry watering means having high liquid-fiow'capacity, 40 .q l PQW Qg therelationship r-pfifvious ability to remainopen andfunction withoiit'cldgsup i a for granular materials being "mg, and ability to retain the fines desired so re ented o the Pulp; y y that little or none of the desired product'is lost F 7. .i Sectional e l Similar to t Of or returned to the circuit. i igFljand showing a somewhat modified form Still another object of the invention is to pro- ,45 "of jbucket structure," as indicated by the line, 1 1 vide a device in which suction is relied upon of Fig. 8;' forthepurpose of removal of, the desired pro- Fig. 8 is a section takenapproximately on the portion of liquid from the solid' material, and finely-8 of, Fig. 7; I i

air -or other gas under'pressure is relied upon j FigLBA is a sectional detail showing a slight to insurepositive dis barge of the so driedfs'olid 59 'modiiication of the' bucketlof Figs. '7 and 8;

V Fig; 9 is an elevational view similar to that of Fig. 1 and shows a modified form of apparatus; and

Fig. 10 is a plan view of the apparatus of Fig. 9.

As illustrated, especially in Figs. 1, 2 and 3, the apparatus comprises a wheel or rotary bucket type of conveyor generally indicated at C which is mounted to rotate between opposite portions of a framework generally indicated at F, the

lower portion of the bucket conveyor dipping into a sand or similar pulp P contained. within a rectangular pulp-receiving tank T which acts as a classifier and is open at its top. The periphery of the conveyor C is provided with a plurality of buckets generally indicated at B adapted to pick up a predominant proportion of solids which settle in the tank T. A modified form of bucket B2, as show at the top of Fig. 3 and in Figs. '7 and 9, also, may be used.

The framework F comprises a plurality of standards l and a plurality of standards I l, the standards I0 carrying appropriate supporting cross bars 12 and the standards I carrying various platforms i3 and M. One of the bars l2 at an intermediate portion of the framework F on each side of the conveyor C carries the respective end of a shaft i5 of the conveyor C, appropriate bearings I6 serving to journal the ends of this shaft as seen in Fig. 1. The middle portion of the shaft l5 has afiixed thereon a pair of spaced hubs I? which support and drive spaced, disc-like plates l8 of theconveyor C, the outermost portions of the plates I8 being joined in the form shown to frusto-conical connection walls it, the outermost portions of the walls is being in turn secured to annular end plates which constitute peripheral portions of the conveyor C.

For the purpose of driving the rotary conveyor 0, the platform l3, which is located at one end of the structure asindicated in Figs. l and 2, .1

carries a motor 22 which drives a chain 23 passing over a sprocket 24 mounted upon a drive shaft 25 having a pinion 25 meshing with a gear 28 secured upon one end of the conveyor shaft l5. Mounted at one side of the apparatus upon the platforms l4, which are located adjacent both ends of, the apparatus, are air pumps 30 which are driven by motors 3! through the medium of belts 32 and pulleys 33, each pump supplying a high pressure air line 34 at its discharge side, and re:- ceiving through a suction line 35 and a T 35a at its intake or low pressure side, for the purpose of successively subjecting the buckets B to suction and high pressure effects as later to be described. The line 35 and T 35a have adequate capacity for handling a suction air stream in addition to water being withdrawn from the buckets B. At the side of the apparatus opposite the pumps 39 high pressure water supply pipes 35 (Fig. 1) are positioned for the purpose of supplying water under pressure to each end of the conveyor C in Fig. 5, or may be separate .end Walls 40a as in the .forms of Figs. 8A, 9 and 10. .One construction for each of the buckets B, which is best de- 5 tailed in Fig. 4, includes a generally fiat, out- The opposite or outer wardly disposed'side wall 4| which is angularly positioned with respect to the corresponding radius, the upper extension M12 of the side wall 4| being roughly perpendicular to the corresponding radius. Opposed to the side wall 4| of each bucket is a generally fiat, inwardly disposed side wall 42 arranged approximately perpendicular to the corresponding radius. One end of this wall 42, which may for convenience be termed the lower end, is rolled to provide a curved portion 42a which is welded to the adjacent portion of the wall 4| and may be termed a curved bottom portion. The side walls 4| and 42 in general provide the bottoms of the respective buckets B when the buckets serve as containers, the actual effective bottom portions varying as the buckets change their positions during rotation of the conveyor C in the direction of the arrows shown in Figs. 1 and 3.

The curved bottom portion 42a of each wall 42 slopes laterally outward from the respective partition 49 to the respective end plate 20, so that the lowermost end of the curved portion 42a communicates with and drains to a corresponding opening 4-4 in the respective end plate 20, such opening 44 constituting a passage for air and liquid. Thus, each end plate 29 is provided with an opening 44 for each of the buckets B, these openings 44 being adapted to communicate successively with suction and pressure manifolds and alternately with the atmosphere. The advancing portion of each bucket B, which is opposite from the curved bottom portion 42a and therefore may be considered the top of the bucket, is necessarily open both for the reception of pulp and for the discharge of de-watered solids. As also seen in Fig. 4, the edge of the wall 42 opposite from the curved bottom portion 42a is sealed against the lowermost edge portion of the outer wall 4| of the immediately preceding bucket B. This sealed joint may be effected by welding, as may the other joints between the various parts of the buckets.

.At an intermediate position in each of the buckets B there is disposed a supporting wall 45 for solids being de-watered. This wall '45 is removably mounted in its respective bucket,

and this is accomplished by welding an angle bar 46 to the inner face of the outer side wall 4lof the respective bucket and another angle bar 4'! to the wall 41 of the adjacent bucket. The edges of the supporting wall 45 are flanged to engage the angle bars 46 and 41 and are secured in place by means of short bolts 48 which are threaded into nuts 49 welded in place on the under sides of the respective angle bars.

Thus, the bolts 48 may be easily removed with socket wrenches in order that the respective supporting wall 45 may be replaced. The ends of each wall 45 are sealed against its partition 40 and the adjacent, portion of the respective e'nd'plate 20 by any appropriate means. Each supporting wall 45 is provided with a series of rectangular apertures 50 in which are positioned various groups or tufts of bristles 5| of common rectangular brushes having rectangular backs 52. The tips of the bristles 5| of each brush provide a fiat filter surface and are confined against spreading laterally by the edges of the wall 45 of the respective aperture 50. The bristles 5| are positioned in their apertures 50 and the respective brushes are held to maintain such position by wood screws 53 which are screwed into thebrush backs 52 and are received in positioning straps 54 whose ends are offset and riveted or otherwise appropriately secured to the respective supporting wall as indicated at 56, or are secured by the bolts 48. The base of each tuft of bristles 5Iis compacted by drawing the bristles together and securing the tuft base in the respective brush back 52 i in a conventional manner. When suction is applied through the respectiveopening 44 to the chamber 58 enclosed by the-various walls 4|, #2 and 45, whereby to draw water through the bristles 5|, the latter serveas a very effective barrier and filter medium which prevents the sand or other granular materialor similar solids from passing through the lower portions of the tufts with the water. Also, the bristles rather readily release granular particles by a subsequent blowing operation wherein air under pressure is passed in a reverse direction through the bristles 5|, as well as by a subsequent washing operation where water under pressure is similarly passed through the bristles in such reverse direction;

As the bucket conveyor C advances to move the respective openings 44 of the various buckets B in the direction indicated by the arrows shown in Figs. 1 and 3, some of the excess water may first drain out through the bristles 5!. This continues until any given opening 44 comes into communication with a channel 60 in a suction manifold 61 which contacts the'respective end plate 20 and is connected to the suction line 135 andT 35a leading to the intake side of the respective pump 30. Thus, suction effects are produced in each of the buckets B as long as its opening 44 communicates with the suction manifold 6|, suction continuing until the bucket has passed slightly beyond top center as viewed in Figs. 1 and 3. The respective opening 44 is then exposed to the atmosphere for a short interval, following which it comes into communication with an air channel 62 in a pressure manifold 63 supplied with air under pressure from the high pressure line 34 by way of a line 34 This air pressure assists in loosening the sand or other de-watered solids so that the solids are discharged to a chute 65 or the like illustrated in Fig. 3. During this discharging stage the outer surfaces of the various outer side walls ii serve as means to direct the solids being discharged to the chute 65. The air under pressure also serves at this time to clear out most of the sand from the bristles 5|.

. Any given bucket B having been emptied of its de-watered solids, its opening 44 passes from the air manifold 63 and, following an interval of communication with the atmosphere, arrives at a high pressure water manifold 66 (Fig. 1) having a channel 61 which communicates with the corresponding water supply pipe 36. The high pressure water entering through the respective opening 44 fills the respective'chamber 58 and then passes through the bristles 5| of the brushes whereby to dislodge and washout any solid material remaining in the bristles. This wash water, together with accompanying "solids, is discharged into the tank T at the left side of. the apparatus as viewed in Fig.3.. If desired, each water manifold 66 may extend down into the pulp P in the tank T so that. a portion of the washingmay take place after submergence of the respective bucket B.

I In "order to maintain an (adequate sealing between each of the manifolds BI, 63 and 66, with the annularend plates 20 of theconveyor C, ap-

pro at p cki g; mea s!!! tri 211s. secured to flangedportions of the manifolds many man ner appropriate for sliding engagement with.the

' of the standards 10.

. byfrom-the bristles 5|.

end plates 20. Such packing material may be in the form of rubber layers vulcanized or otherwise suitably secured, such rubber being natural or synthetic, as most desirable or other acceptable packing materials andarrangements may be used.-To insure adequate contactof the manifolds 6!, 63 and 66 and their packing material. '10 with the plates 20, assisting means may be provided, such asspring controlled pressing devices 1 2 illustrated in Fig. 2, these devices being carried in appropriate sockets 13 or other holders mounted upon the upper cross bars I2 at the tops Bracket means 14 (Fig. 2) may be employed for proper positioningof the various manifolds. In the case of the manifolds 66, means such as brackets 15 (Fig. 1) carriedby adjacent portions of the tank T may serve to carry suitable assisting means corresponding with the devices 12. l

-The high pressure water introduced through the manifolds 56 is returned to the tank T for the purpose of recovering solids removed there- The water withdrawn through the suction manifolds BI is receivedby traps 16 (Figs. 1 and 2) into which the water is delivered by drainage pipes 76a which connect with the high pressure lines 34 and Ts 35a positioned at the bases of the suction manifolds 61. The water may be returned from each trap 16 to the tank T, as by a line 11 and a pump 18 (Fig. l), to provide a suitable water flow for classification purposes, or as described below in connection with the form of Figs. 9 and 10. Again, the water may be discharged to waste as through a line 19. Any appropriate liquid head may be established to offset the pull of the vacuum pumps 30.

Pulp to be de-watered is supplied to the tank T at any appropriate point such as the inlet indicated at 80 (Fig. 3), and a baffle 8i is preferably employed to direct the solids downward and to some extent segregate the feed from the moving buckets B. The water level is maintained at any satisfactory height to obtain desired classification of the pulp in the tank '1. i This may be established by overflow laundersor troughs 82 (Fig. 2) through which leaves, small sticks, and other waste and fines may be discharged from the system in the excess water. The troughs 82. are carried upon appropriate brackets 82a, within the tank T and are provided with vertically adjustable upper edge strip members 83 which are mounted as by bolts and slots 83a to vary the overflow level or the effective length of the trough edges passing overflow water and, hence, to vary the relative agitation or quiescence in the tank T as the nature of the feed requires. Such overflow water is discharged from the system by means of drainage pipes 84 leading from the bottoms of the troughs 82 and passing outward through the sides of the tank T. Thus, as heavily watered pulp is fed into the tank ;T and the solidssettle in the bottom of the tanlnthe accumulating, supernatant water and light materials separated from the desired solids escape.

If necessary, the strip members 83 may be angu larly'adjusted to serve as levelling means for the tank troughs 82, if the apparatus is not level, or they may be angularly or vertically adjusted to vary the proportion of the trough edges over whichtwater may flow by raising corresponding portions of the members 83 to positionsabove the pulp level, thereby also varying the effective top 2&7 6,128

ar a f t ectiv risi c lumn and urther vary the agitation, settling and classification, as well as, varying the ellective stream length of the moving pulp within the tank T. All of these factors may be relied upon to regulate classification.

As the bucket conveyor C rotates in the indicated direction, the various buckets B (B2) scoop up settled solids from the bottom of the tank '1' together with a relatively large amount of liquid, such solids being caught in the buckets as their mouths approach the top of the tank T. Water which separates and passes through the bristles 5] by gravity as the buckets are lifted above the liquid is drained back into the tank T by way of the openings 44, until such time as the respective openings 44 pass to the channels 69 in the suc-; tion manifolds 6|, whereupon the suction effects draw the liquid, freed from solids, through the bristles 5|, such liquid draining into the traps I6 as above indicated. The liquid having been removed by the preliminary gravity drainage and by the succeeding suction operation, the openings 44 leave the manifolds 6] and, after a brief communication with the atmosphere, pass to the manifolds 63. At approximately this position the de-watered solids tend to fall from the respective buckets B, and this is assisted by the air streams passed through the bristles 5i under influence of the high pressure air supplied by the high pressure line 34 and the connecting line 34a. A very small proportion of de-watered solids tends to stick in the bristles 5! after the dumping and blowing operations and this is flushed out next by high pressure water received through the water manifolds 66.

When desired to increase gravity separation of excess water picked up in the buckets, a modified form of bucket B2 (illustrated at the top of Fig. 3 and in Figs. 7 and 8, and similarly in Fig. 9) may be employed. Here substantially the same side walls 4I and 42 are employed as in the other form, and substantially the same supporting wall 45 located above the suction chamber 58 is employed for each bucket B2. In this instance the walls as and M may be secured to the end plates 26 by means of rivets 85 and flanges 86. However, in this form the side wall 42 has an extension 81 whose upper edge portion is bolted to the lower edge of the side wall M of the preceding bucket B2, and whose intermediate portion is provided with a series of relatively large openings 38 filled with banks of louvers 90 which are sufficiently closely positioned to retain solids being handled. These louvers may be integrally formed by striking up from suitable metal plates 9| whose edges are bound into position by screws or bolts 92, or the louvers 90 may be formed in any other appropriate 'manner. Thus, the spaces between the louvers 90 are disposed to discharge supernatant water back to the tank T through the interior of the wheel or rotary conveyor C, this return being necessary inasmuch as such drainage water will necessarily contain some solids which need to be recovered. Such water reaches the tank T through the louvers 90 andthe sand-receiving portions of those buckets which are then submerged in the tank I. By employment of the banks of louvers 90, a large proportion of the excess water picked up'from the pulp bed in the tank T by the rising buckets as the conveyor C rotates flows out through the louvers and correspondingly reduces the load required of the suction system. Also, as the body of solids tends and an tofall forward durin rotation of each bu ket. tie-Watering Will be further facilitated by draine through the louvers .90. The operation of this modification of the buckets B is similar to that of the other form, but a larger proportion of the excess water is separated by gravity drainage... This indicated return of water from the buckets B and B2 insures an adequately large water supply to classify and wash the solids, as required, before they pass into the buckets, and adjustment of the edge members 83 regulates the classification.

In the form of apparatus shown in Figs. 9 and ID, the buckets B2 are of substantially the same construction as those of Figs. 7 and .8, as presently to be described, but the construction of the bucket conveyor, generally indicated at C2, is somewhat different from that of the bucket conveyor C of Figs. 1 to 3, and the means for handling the returning water is different.

In Figs. 9 and 10, a tank T2, which is of rectangular design and open at its top corresponds with the tank T .of the other form and has the rotary bucket conveyor C2 arranged so that the buckets B2 dip into the water bearing pulp as in the other form of construction. A framework F2, of somewhat simpler construction than the framework F of the other form, is shown as comprising standards III] at opposite sides of the tank T2 to support the conveyor 02, and the standard II I disposed adjacent the standard H0 on the driving side of the apparatus, the standard III being connected with an intermediate portion of the standard II 0 by means of a crossbar II2.

The conveyor C2 is actuated and supported through the medium of a shaft II5 whose opposite ends rest in appropriate mountings H6 mounted upon the tops of the standards IIB. Adjacent the mountings IIB, the shaft H5 is provided with a pair of spaced hubs I I1 (Fig. 10) provided in disc-like plates H8 which constitute the ends of a driven drum H9 which is indirectly connected to annular end plates I20 intervening partitioning plate I20a, also of annular formation. The end plates I 20 and the partitioning plate I20a together with the buckets B2 and the driven drum II9 constitute the principal portions of the conveyor C2. In the form shown, the inner edges of the plates I20 and I2'Ila are affixed to a driven drum |2I whichis concentric with the driven drum I I9, and the two drums II9 and I2I are rigidly connected in driving relation by means of interposed annular rings I22 welded in position, as shown, so that the conveyor C2 as a unit may be driven through the medium of the drum H9. In order to effect such driving of the drum II9, a sprocket I24, adapted to be driven by an appropriate chain from any prime mover (not shown) is provided upon a sub-shaft I25 mounted in a bearing I25a on the top of the previously mentioned standard III. The inner end of the sub-shaft I25 has fixed thereon a pinion I26 which meshes with a large ear I28 which is appropriately fixed to the adjacent end of the driven drum III! projecting beyond the tank T2. By these means the bucket conveyor C2 is rotated upon the supporting shaft H5, on the mountings I I6 as above indicated.

The buckets B2, which are substantially the buckets of Figs. 7, 8 and 8A, have the same louvers formed in the same metal plates 9| provided in the same extensions as the same side walls '42 of the buckets and with substantially the same outward sidewalls 4I, dla, whose outer surfaces serve to guide the de-watered solids of the respectively succeeding buckets as the solids are discharged following rotationbeyond top center of the conveyor. As indicated, the ends of the buckets B2 may have the separate end walls 45a seen in Fig. 10, and corresponding generally with the end walls 40a of Fig. 8A, or their end walls may be provided by the end plates I20 and the partitioning plate I2Ua in general conformity with the construction shown in Figs; 5 and 8 where the end plates I20. and the partition 40 are employed as ends of the buckets B. Also, substantially the same intermediate supporting walls 45 are employed to carry the same rectangular brushes composed of tufts of bristles 5! and brush backs 52 as in the other form and as illustrated in greater detail in Figs. 4 to 7, inclusive. However, the rearward or bottom portion of each of the inward walls is directed more distinctly radially outward than is the curved bottom portion 42a of the form of either Fig. 4 or Fig. '7, such radially directed portions being indicated at 142bin Fig. 9.

Since the mechanism for producing suction in the buckets B2 of the conveyor C2 of Figs-9 and 10 is located at the central or hub portion of the rotary conveyor 02, the means for producing partial vacuum effect in the chambers 58 of the respective buckets are made in the form of conduits I which are directed substantially radially inward as best seen in Fig. 9 and are connected'with the chambers 58 adjacent their outer ends as best seen in Fig. 10. The inner ends of the conduits I35, which oorrespond in a, general way with the outlets 45 from the chambers 58 of the structure in Figs. 1 to 5, are rigidly connected to theoutei driven drum I2I at positions outside of the end annular driving rings I22 (Fig. 10). These connections are made by appropriately fitting the ends of the conduits I35 in openings I35 provided in the respective end portions of the drum IN. The ends of the conduits I35 are thus adapted, as the conveyor C2 rotates in the. direction of the arrows seen in Fig. 9, to communicate with at least one of a series of peripheral openings I38 provided in an annular valve I which is nonrotatably mounted upon each, end portion of the inner driven drum H9. The series of .openings I38 in each annular valve M0 extends through that portion of the periphery, of therespective valve. .member I40 which corresponds;

with that portion of the path of travel of each bucket B2 during which the suction chamber 58 of the respective bucket.:B2 is to be placed, under partial vacuum. This range extends from; approximately the horizontal as seen at the right:

of Fig. 9 to a .position somewhat beyond top center as is .illustratedat the upperleft of Fig. 9.; The rest of'the peripheral portion-of each valve I55 is imperforate so that suction "is cut oil as any given bucket B2 moves over to discharging;

position and is not restored until the bucket has passed through the tank, picked up its load of sand, and risen to a position above the, water level in-the tank, or approximately to a horizontal position. between the annular valves I4!) and the conduits I35, appropriate annular sealing means 142 is employed between each annular valve I40 and In order to seal the connectionsthe respective end of the outer driven drum I2I. Each valve I4il,"which acts as a manifold, is

hollow as seen in the top of Fig. 10 and extends 1O outward alongthe inner driven drum H9 to a position where its upper portion is connected with oneend of an upper suction conduit I through which air moves, and for connection of its lower portion with a lower suction conduit I46 through which water sucked through the brushes 5|, 52 is removed. 7

The conduits I45 and I45 extend rearward along the ends of the bucket conveyor C2 to a receiving chamber I48 which is placed under partial vacuum by an appropriate vacuum pump I50 which may be mounted on the top thereof. The, valves hit, being rigidly connected to the forward ends or the conduits I45 and I46, are held against rotation, inasmuch as the opposite ends of theconduits I45 and I46 are held against movement by reason oftheir attachment to the chamber I48. Water returning through the lower conduit I 35 falls into the bottom of the chamber I48 where it is appropriately removed. Preferably the water is picked up by a centrifugal pump I52 (Fig. 9) driven by a motor M53 or the like on top of the chamber I48 and forced through'lines I54 along the opposite sidesof the tank T2 to discharge points near the forward supply for any required classification oi the feedmaterial, such as sand, before the desired solids are picked up by the buckets B2.

When the classified sand is picked up in a bucket B2 settling promptly occurs, and the su-- pernatant water proceeds to flow out through the louvers as soon as the bucket moves above the water level. At this stage. the inner ends of the conduits 35 within the rotary conveyor C2 come into communication with the valve openings I38 in the adjacent portions of the stationary annular valves lilil. Also, at this stage, the partial vacuum created in the system by the vacuum pump I50 begins to draw remaining water through the ristles 5! on the brush backs 52, the water passing into the hollow valves I45 and falling into.

the receiving chamber I48. As long as any supernatant water remains it continues to flow through the louvers 9G, and residual water continues to be removed by the efiect of the partial vacuum inthe system until the respective suction conduit has passed beyond the last valve opening I38 in'the direction of travel of the conveyor C2. At. this stage, the ole-watered sand begins to fall from the respective bucket B2, slide down over the adjacent outer wall4-I of the preceding bucket,. and is discharged from the apparatus over a chute.

I65 correspondinggenerally with the chute. 65 of Figsfl and 3.

As best indicated in Fig. 10, the feed materials are introduced into this form of apparatus at the'forward end of the tank T2 adjacent both corners thereof near the ends of the chute I65.

These feed points are indicated at I80. As in the caseof the form of Figs. 1 to 3, the water level is determined by overflow troughs I82 extending longitudinally of the tank T2 at opposite sides' thereof beyond the ends of the conveyor C2 at elevations somewhat above the points of discharge of the returning fiitrate through the return lines 154. These overflow troughs I32 extend substantially the entire length of the tank T2 so that they may adequately remove surface water and adequately efiect desired classification of the feed material. In order to vary the settling rate and thereby vary classification as required, the sides of the troughs I82. are provided with vertically ad-1v justable edge strips I83 corresponding with the adjustable edge strip members 83'of the other form. Thus, as the edge strips I83 are raised or lowered through the medium of any adjustment means such as bolts and slots I84, lesser or greater amounts of fines and other light materials are caused to overflow into the troughs I82 and thereby regulate the character of heavy material moving to the middle of the tank and picked up by the buckets B2. The troughs I82 discharge into a receptacle 85 which may in turn be discharged through an outlet I86.

In all forms, raising and lowering of the edge strips 83, I83 vary the pulp head in the tanks T, T2 and correspondingly affect the settling rate of the solids, as will be apparent to those skilled in the art. Again, raising of portions only of the edge strips 83, I83 may be relied upon to decrease the overfiow length along the tops of the troughs 82, I32, and thus decrease the effective area of the rising liquid columns and affect the settling rate and classification accordingly. This will be further affected by theconsequent lengthening or shortening of the path through which the liquid must pass to the overflow points.

It will be evident from the foregoing that the classification of the feed material, and the removal of water from the sand picked up by the 'buckets B2, are substantially the same as in the other form of the invention. As previously described in connection with the bucket structure B2 of the form of Fig. 7, the supernatant water flowing out through the louvers 90 falls within the rotary conveyor C2, and thereby returns to the tank and to the buckets any sand which may have escaped through the louvers 90. Such falling water and sand returns to the buckets through the louvers 911 in the same way in which they escape therefrom.

In all instances, the substantially fiat filter surfaces presented by the tips of the bristles SI of the various brushes serve perfectly to retaineall sand, possibly aside from very fine materials which escape classification, and to permit the passage or" water under the influence of the suction of the system without clogging of the brushes. This filtering means, wherein the tips of the bristles are confined by the edges of the respective openings 50, surpasses ineffectiveness all other filtering agencies, both from the standpoint of speed and thoroughness. In addition, the present apparatus, by reason of the described classification features and characteristics, eliminates the necessity for the employment of a separate classifying agency before passage of the feed material to the tank supplying the buckets.

The return of the water by the pumps of both forms of the invention into the classifying tanks T and T2 below the pulp assists rather than retards classification, and the return through the wheel conveyor of water escaping from the buckets through the louvers 90 avoids disturbance of the classification zones by the falling water, while the passage of such returning water back through the louvers aids in rejecting unwanted fines at the pickup point of the buckets. Again, any desired sand returned to the vacuum chamber I48 and thence to the tank by thelines I54 is thereby recovered.

In operating the rotary de-watering structure of either form of this invention, I have found it possible to reduce the water content of a pulp containing about 80% water to a water content of only about 5% with a vacuum in the order of 6 inches to 7 inches of mercury. In employing has a diameter of fourteen feet and eighteen buckets are provided in each circular series, a capacity of 250 tons per hour has been reached.

Since variations of the specific forms disclosed will become apparent to those skilled in this art, it is intended to cover all such modifications as fall within the scope of the patent claims.

I claim as my invention:

1. In combination in a classifying and dewatering apparatus: a classifier tank adapted to receive a water pulp containing solids to be classified and de-watered; a rotary conveyor; and buckets arranged on said conveyor about its periphery for dipping into said tank to pick up pulp in said tank, said buckets having waterpervious wall portions capable of supporting solids while passing water therethrough, said conveyor comprising substantially solid end walls between which said buckets are mounted, said end walls and buckets substantially enclosing the interior of said rotary conveyor, at least certain of said water-pervious wall portions discharging into said enclosed interior of said conveyor, whereby water discharged thereby does not fall into the portions of pulp being classified in said tank, said end walls having outlets, and water discharging means communicating with said outlets to remove water therethrough.

2. A combination as in claim 1 wherein said certain of said wall portions are disposed to serve as side walls of said buckets as the latter rise, whereby supernatant water flows therethrough, and wherein other water-pervious wall portions constitute bottom portions as said buckets rise and include filter members for passage therethrough of drainage water from solids supported thereon.

3. A combination as in claim 2 including differential air pressure means connected with said filter members for passage of drainage water therethrough, and means for conducting such drainage water beyond the surface of the pulp undergoing classification in said tank.

4. In combination in a device of the class described: a classifier tank having fiow control means to provide desired classification; a rotary wheel-type conveyor dipping into said tank and having end walls; a plurality of buckets fixedly mounted at the periphery of said conveyor between said end walls, said buckets having waterpervious walls; means providing chambers for reception of water passing through certain of said pervious walls; duct means connected with said chambers to place the latter under. differential such dischargedwater may fall upon inner walls of lower buckets.

6. A combination as in claim 4 wherein said end walls of said conveyor have ports communi- V eating with said chambers, and the said duct References Cited in the file of this patent Number UNITED STATES PATENTS Name Date Kier May 21, 1912 Trent May 26, 1914 Willard Aug. 31, 1915 Engel May 11, 1923 De Reamer June 12, 1928 Graham Oct. 16,1928

Burhams Nov. 24, '1931 Number Number 10 211,475 347,969 455,718

Name Date Chaplin Mar. 1, 1932 Durgen Feb. 19, 1935 Hunter Oct. 3, 1939 Buckbee June 22, 1943 Abbrecht Apr. 26, 1949 FOREIGN PATENTS Country Date Germany July 11, 1909 Germany Jan. 28, 1922 Germany Feb. 10, 1928 

